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Revision 9b938c72

ID9b938c7262e403f5467110609cb20ef1ae6e9df2

Added by Stefan Hajnoczi about 11 years ago

chardev: clear O_NONBLOCK on SCM_RIGHTS file descriptors

When we receive a file descriptor over a UNIX domain socket the
O_NONBLOCK flag is preserved. Clear the O_NONBLOCK flag and rely on
QEMU file descriptor users like migration, SPICE, VNC, block layer, and
others to set non-blocking only when necessary.

This change ensures we don't accidentally expose O_NONBLOCK in the QMP
API. QMP clients should not need to get the non-blocking state
"correct".

A recent real-world example was when libvirt passed a non-blocking TCP
socket for migration where we expected a blocking socket. The source
QEMU produced a corrupted migration stream since its code did not cope
with non-blocking sockets.

Signed-off-by: Stefan Hajnoczi <>
Reviewed-by: Eric Blake <>
Signed-off-by: Luiz Capitulino <>

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